With the N9, Nokia stumbled onto a phone design it really fell in love with, and since then we’ve seen the same type of polycarbonate frame become a staple of the company’s forays into Windows Phone. While that feels like a big part of what makes a phone a Lumia, could Nokia already be thinking of finding a new look for its next Lumia headliner? That’s what some new rumors are suggesting, saying that Nokia could be looking to create a sleeker, slimmer, and lighter Lumia thanks to a move to aluminum construction.

This won’t necessarily be an all-or-nothing move, and we could still see the old PC designs continue to find a home alongside this new metallic look, but sources claim that at least one of these aluminum-bodied phones, codenamed Catwalk, is in the works.

Catwalk is supposed to be the follow-up to the Lumia 920, though by the sounds of it not much is changing besides the handset’s shell; these reports have Catwalk featuring internal hardware substantially similar to what’s already available. Alongside it, Nokia is also supposed to have two other new Lumias under development, though we’re at a loss for details about their hardware and construction.

As for a timetable, all we have for now is that Catwalk is due sometime in 2013. If we had to guess, a release in late spring might make a lot of sense, but for now nothing’s certain.